Fig. 2
From: Pseudo-spin–valley coupled edge states in a photonic topological insulator
Edge states between valley–Hall and quantum spin–Hall domains. a, b Edge band diagram of a 40 × 1 supercell, with an interface between the rod-collar-lattice with collars in contact with the lower plate and triangle-lattice. There are two gapless edge states which correspond to pseudospin-up (↑, red line) and down (↓, blue line) states at the K′ and K points, respectively. The bandgap spans the frequency range from 20.3 to 21.3 GHz. c Transmission spectra along the straight and bent paths. The shaded region indicates the bandgap. d Transmission spectra through the bulk of the rod and triangle lattices
